Pigs as natural hosts of Dientamoeba fragilis genotypes found in humans

Dientamoeba fragilis is a common intestinal parasite in humans. Transmission routes and natural host range are unknown. To determine whether pigs are hosts, we analyzed 152 fecal samples by microscopy and molecular methods. We confirmed that pigs are a natural host and harbor genotypes found in humans, suggesting zoonotic potential. The flagellated protozoan Dientamoeba fragilis is one of the most common parasites in the intestinal tract of humans. Infection is highly prevalent in economically developing regions and in industrialized countries. Infected persons often show no symptoms, but a pathogenic role for this parasite has been reported recently in humans and gorillas. Little is known about transmission routes of this parasite, and a transmissible stage (e.g., a cyst) has not been described. Molecular characterization of human isolates based on sequence analysis of ribosomal genes revealed 2 genotypes (1 and 2), with genotype 1 predominating worldwide.

Other than humans, few animal hosts of D. fragilis have been reported. Surveys of mammals and birds have identified only nonhuman primates (gorillas, macaques, and baboons) as natural hosts. Recently, however, a high prevalence of infection (43.8%) has been reported in pigs in Italy. To determine whether pigs are a host of D. fragilis, we analyzed fecal samples from 152 pigs in Italy by microscopy and molecular methods.

Emerging Infectious Diseases
May 15, 2012

Original web page at Emerging Infectious Diseases